Screw machine



J. l-l. MANsFlELD 2,327,279

SCREW MACHINE Filed June 1 1942 6 Sheets-Sheet 1 NWN.

Augo 17, 1943.

Aug. 17, 1943. J. H.MANsFlELD SCREW MACHIN E Filed June l, 1942 6 Sheets-Sheet 2 Nhw.

Aug. l?, M43. J. H. MANSFIELD SCREW MACHINE Filed June l 1942 6 Sheets-Sheet 5 NW huw NLSN @N www w Aug 17, 1943., J. H. MANSFIELD 2,327,279

SCREW MACHINE Filed June l, 1942 '6 Sheets-Sheet 4 INVENToR.

1942 6 Sheets-Sheet 5 Aug.. E7., J. H. MANSFIELD SCREW MACHIN E Filed June l Auge Tl?, W43.' J. H. MANSFIELD SCREW MACHINE Filed June l, 1942 6 Sheets-Sheet 6 IN VEN TOR Patented Aug. 17, 1943 SCREW MACHINE Judson H. Mansfield, Rockford, Ill., assigner to Greenlee Bros. & Cio., Rockford, Ill., a corporation of Illinois Application June l, 1942, Serial No. 445,329

(o1. lei- 130) 2li Claims.

The invention relates generally to automatic screw machines and more particularly to the thread cutting means thereof.

One object of the invention isV to provide a new and improved screw machine by the provision of new and improved drive means and control means for the tap or die carrying spindle.

Another object is to provide in an automatic screw machine driving means for the tap or die carrying spindle that is simplied yet capable of operating smoothly and quietly at high speeds.

Another object is to provide, in an automatic screw machine having a work or stock spindle, a tool spindle frictionally rotated at the speed of the work spindle and means for rotating the spindle at a speed aboveor below the work spindle speed.

Another object is to provide, in an automatic screw machine having a work spindle and a tool spindle, means for driving the tool spindle to rotate at the speed of the work spindle and alternatively operable clutches to rotate the tool spindle at a speed above or below the work spindie, the clutches and drive means for the tool spindle being constructed to permit speedy and continuous transition from drive by one clutch to drive by the other without pause at the point when both clutches are disengaged.

A further object is to provide new and improved control means for the tool spindle driving means.

Still a further object is to provide, in a screw machine having a pair of clutches for driving a tool spindle, control means including a load and re device potentiated by engagement of one of the clutches and released under the control of the tool spindle but thereafter operating under its own stored energy to disengage the one and engage the other clutch.

Other objects and advantages will become apparent from the following detailed description taken in connection with the accompanying drawings, in which:

Fig. 1 is an enlarged and partial longitudinal sectional view through the tail end or spindle casing of a multiple-spindle, automatic screw machine, taken approximately along the line I -l of Fig. 7.

Fig. 2 is a view partially in plan and partially in section through the spindle casing, taken approximately along the line 2-2 of Fig. 7; The spindle shown in section is not the spindle shown in Fig. 1, but a spindle identical therewith in construction.

Fig. 3 is a rear elevational vview of the tailstock end of the Vmachine with a part of the spindle casing in section better to reveal certain internal construction.

Fig. 4 is a transverse sectional view taken approximately along the line 4--4 of Fig. 3.

Fig. 5 is a fragmentary detail view of certain control mechanism, taken approximately along the line 5--5 of Fig. 4. l

Fig. 6 is a fragmentary detail View taken along the line 6--6 of Fig. 5.

Fig. 7 is a transverse sectional view through the spindle casing, taken approximately along the line 1 1 of Fig. 3.

Fig. 8 is an enlarged transverse sectional View taken approximately along the line B- of Fig. l.

Fig. 9 is a fragmentary detail view taken approximately alongthe line 9 9 of Fig. 4, and showing the mechanism in one operative position.

Fig. 10 is a view similar to Fig. 9 showing the mechanism in a diierent operative position.

Fig. 11 is a view in perspective and somewhat diagrammatic of the drive train for certain parts of the machine.

While the invention is susceptible of various modications and alternative constructions, it is shown in the drawings and will hereinafter be described as embodied in an. automatic' screw machine. It is not intended to limit the invention to the speciic construction disclosed, but to cover all modifications and alternative constructions falling within the spirit and scope of the invention as defined in the appended claims.

For purposes of disclosure, the invention is here shown as embodied in a multiple-spindle, automatic screw machine. Such a machine has a bed 2U formed with ways 2l (Fig. 4) extending longitudinally thereof and upon which is reciprocable a slide 22 (Figs. 3, 4 and 11). At one end, normally the right hand or tail end, as viewed from the front of the machine, the bed 20 supports a casing 23 which houses certain spindle actuating mechanism and will thus hereinafter be referred to as the spindle casing. Extending from the spindle casing 23 toward the headstock, diagrammatically indicated at 24 in Fig. 11, is an overarm 25, and depending from this overarm near the middle thereof is a bored bracket 2t the purpose of which will presently be made known.

As above stated, the machine disclosed herein is a multiple-spindle machine, such multiplicity of spindles, six to be exact, is shown in Fig. 7. However, inasmuch as all of the spindles associated with the spindle casing 23 are of identical construction and inasmuch as this invention is applicable equally to a single or a plurality of spindles, only a single spindle is shown, in other than Fig. '7, in order to clarify the views. Accordingly, there is shown as projecting from the spindle casing 23 in Fig. 3 a single spindle, generally designated 21, which projects through and is thus rotatably and reciprocably supported near its outer end inthe bracket 25. This spindle 21 is adapted at its outer or right hand end, as viewed in Fig. 3, to carry a suitable tool 28, usually either a thread cutting die or tap, and will thus hereinafter be referred to as the tool spindle.

The headstock 24 is, as will be readily understood by those skilled in the art, formed with a plurality of spindles, equal in number and axially aligned with the spindles in the spindleI casing 23. One such spindle 29 is shown diagrammatically in Fig. 11, and also shown in that same gure are gears 3c, one for each of the plurality of spindles 2S. Each spindle 29 is, of course, provided with a suitable chuckV 3l for holding a work piece and these spindles will, for convenience in diierentiating from the spindles 21, hereinafter be referred to as work holding spindles.

The tool spindle 21 carrying the tool 28 is rotated and is also reciprocated toward and from the work supported in the spindles 29 of the headstock, so as to cut appropriate threads onA the work piece. This invention contemplates the provision of new and improved actuating :meansy for the tool spindle 21 and new and improved control means for these tool spindle actuating means. These new features of the machine will now be described with such references to the general operation of the machine and to other parts of the machine as may be necessary for a proper understanding of this invention.

As best seen in Fig. 11, there extends longitudinally of the machine from end to end thereof a single shaft 32 (see also Fig. 3) which herein constitutes the main drive shaft for both the work supporting spindles 2S and the tool spindles 21. To that end, the shaft 32 has nonrotatably secured thereon near its left end, as viewed in Fig. 11, a gear that meshes with each of the gears @il so as to drive simultaneously and at the same speed all of the spindles 29. At its right hand end, the shaft 32 carries suitable means presently to be described in detail for actuating the tool spindles. The main shaft 32 is driven from a motor 215 through a suitable drive train including a longitudinally extending shaft 3E having a small gear 31 fast on the end thereof, suitable speed change gears. indicated at 33, culminating in a gear fast on a stub shaft 40, and a gear M (see l) keyed to a short sleeve 42 surrounding the main shaft 32 and in turn made rotatable with the shaft by a diametrically extending pin 43. Also driven to be actuated in timed relationship with the spindles 29 and the spindles 21 is the slide 22. The drive for the slide 22 commences with.y the stub shaft 40 and includes a worm 45 on the end of the shaft 4D, worm wheel 4S, shaft c1., change gears 48 and 49, shaft worm 5l, worm wheel 52, shaft 53, worm 5A, worm wheel 55, shaft 56,. and segmental gear 51 adapted to engage successively with racks 5S and 59 formed on the slide 22. It is believed apparent from this construction that, as the shaft 32 rotates to drive spindles 21 and 29, slide 22 will first be advanced, then remain dem .Awa-... mm

in its advanced position during a dwell period, and thereafter be returned to initial position, such movement constituting one cycle of operation of the machine.

Within this cycle of operation the spindle 21 is fed forward to cut the threads on the Work piece and again returned to its initial starting position. Ther provision of mechanism to effect this operation. positively and quickly, yet smoothly and without shock, is a prime object of this invention, and such mechanism will now be described. The tool spindle 21 at its right hand end, as viewed in Eig. l, extends into the spindle casing 23 and at that end has a portion formed externally with longitudinally extending splines 66, and internally is formed with a bore S1. At its extreme end, the portion S5 of the spindle 21 carries internally thereof a nut 63 held in the spindle by ineansof a screw cap E9 threaded onto a reduced, threaded flange on the portion t5. Extending within the bore 61 and engaged by the nut 58 is a lead screw 18 terminating at itsv outer or righ-t hand end, as viewed in Fig. I, in. an enlarged hub 1 I. Surrounding the portion t5` of the spindle 21 is an elongated sleeve 12 which at its left hand end, as viewed in Fig. l, is formed with splines 13 cooperating with the splines 55 of the o spindle 21 so as to rotate in unison with the spindle but to permit reciprocation ci' the spindle longitudinally relative to the sleeve. The sleeve 12 is rotatably supported at its left hand end in a ball bearing 14 the inner race 'l5y of which is retained on the sleeve by a nut 15 and the outer race 11 of which is retained by a ring 18 in annular flange 19 projecting inwardly from the inner end wall of the casing 23. Near its right hand end, the sleeve 12 is similarly supported in a ball bearing 3l the inner race U2 of which is retained on the sleeve by a nut 83 and the outer race 84 of which is retained in a right hand end wall 85 of the casing 23.

The lead screw 10 is continuously driven at the same speed and in the same direction, herein counterclockwise, as viewed from the right in Fig. l, as the Work supporting spindles 2Q. For

convenience, this speed will hereinafter be referred to as the normal or intermediate speed. Such rotation is imparted to the lead screw 1U by a positive geared drive including a gear 8B non-rotatably secured on the enlarged hub 1l and a gear 39 non-rotatably secured by a key @il on the extreme right hand end of the main shaft 32. The gear 83' is retained against movement longitudinally of the shaft 32 by bearing against a shoulder Si formed on the shaft 32 and by nuts 92 threaded onto the end of the shaft. Gear 88 is non-rotatably secured on the hub 1i of the lead screw by a diametrically extending pin 93 and is rotatably supported to in turn support one end of the lead screw 1S in a ball bearing 91%. The outer race S5 of the ball bearing is retained in an outwardly extending annular flange 96 by a ring 91, while the inner race 98 is retained on an inwardly projecting annular ilango S9, formed on the gear 88, by a nut H53 threaded ontothe flange. The ring 81, as well as the ring 18, is secured in any convenient manner, herein by elongated bolts lill and H32, respectively, extending through and concealed within the flanges SS and 19.

With the lead screw 10 constantly rotated at a normal or intermediate speed, and with the lead screw. and the spindle 21 interconnected through the medium of the nut G8, and with the spindle and the sleeve 12 interconnected through the rne- 4ported in the spindle 2S.

dium of the splines 56, T3, it will be readily understood that variation in the relative speeds of the lead screw and the sleeve 'I2 will cause longitudinal movement of the spindle 2l. Thus, when the lead screw and the sleeve l2 are rotated at the same speed, no longitudinal shift of the spindle will take place. However, if the sleeve and hence the spindle is rotated slower' than the lead screw, the spindle will be advanced toward the work supporting spindles, that is, tcthe left in Fig. l, and, inasmuch as the Work supporting spindle is rotating in a counterclockwise direction, the tool on the end of the spindle il will cut a right hand thread on the work blank sup- Conversely, if the sleeve 'lli is rotated faster than the lead screw lil, the spindle 21 will be withdrawn or backed off and thus disengaged from the threaded Work blank` To impart these relative speeds to the sleeve 'E2 and hence to the spindle 2l', three drive trains are provided between the main shaft 32 and the sleeve lil. Of these drive trains, the one for rotating,T the sleeve and thespindle at the saine rate as the lead screw lli includes a permanently engaged frictional driving means capable of transmitting the relatively small ainount of required to rotate the sleeve and the spindle at the normal or intermediate speed. To that end, the sleeve "l2 at its right hand end is formed with an extension |55 that projects within and in radially spaced relation to the annular formed on the gear 88. Interposed between the extension li'ili and the flange Sie is the frictional drive, generally designated |85. As best 3, this drive inea-ns is composed of a collar split into semi-circular parts llil and lli-, ued apart by plurality of compression springs seated in recesses ll'i formed in the ends of the collar parts. One of the parts |83 is non-rotatably secured to the extension Il'l or the sleeve '|72 by a key Il l with the frictional engagement of the parte with the gear 38 relied upon for transmission of rotational force from the gear to the collar. The gear 852 is a steel gear, while the collar is made of bronze.

The trains for rotating the sleeve 'l2 at a speed above or below the speed of `rotation of the lead screw 'it are positive trains, capable of overriding the frictional drive means |565. To that end, there is non-rotatably secured on the sleeve T2 a gear .H5 and a smaller gear HG. The gears are non-rotatably held by engagement of internal splines l2 on the gears with external splines ||3 on the sleeve 'l2 and are held against axial movement by set screws IM. The geark ||5 meshes with a gear freely rotatable on the sleeve A2, to which is keyed the main drive gear 4|. Likewise, gear l i Ei meshes with a gear l id freely rotatably mounted on a short sleeve H9 surrounding the shaft 32 and non-rotatably held by a key |25. Preferably, roller bearings l2! and |22 are interposed, respectively, between the gear l l'l and the sleeve 42, and the gear |8 and the sleeve H3. Gear H8 will, of course, be larger than `and the ratios of the gears H5, lll and H5, ||S

will be so proportioned relative to one another and relative to the ratio between the gears 88 and Sli as to rotate the sleeve 12 at a Speed lower than the lead screw when the gears H5, ll'l are eiective, and at a higher speed when the gears HS, H8 are effective.

The gears and ||8 form parts of disk clutches |23 and |24, respectively. Complementary clutch parts of the clutch |23 are nony main shaft 32 by thekey |20.

n of the sleeve.

rotatably mounted upon a short sleeve |25 surrounding and in turn non-rotatably held on the Complementary parts for the clutch |24 are non-rotatably mounted on a similar sleeve |25 surrounding and nonrotatably held on the main shaft 32 by the kei |20. Surrounding and longitudinally slidable on the sleeve |25 is a compound ring |35) having suitable engagement with the complementary clutch means mounted on the sleeve |25 and having a beveled cam surface |31. Pivotally secured by a pin E32 to the sleeve |25 is a short link |33 extending longitudinally of the sleeve and carrying at its other end a roller |34 for engaging the cam surface |3l. Clutch |24 similarly is provided with a compound ring |35 having a beveled cam surface |35 and a link |31 having a roller |33. The clutches are so disposed that the links |33 and itl occupy adjacent ends of the sleeves |25 and 25 so as to be alternatively operable by an annular ring |38 disposed in surrounding relation to the adjacent ends of the sleeves and shiftable longitudinally by means later to be described from engagement with one link to engagement with the other. The inner surface of the ring |39 is rounded so that upon engagement with one of the rollers the roller Will be forced inwardly and in turn, by its action on one of the beveled cam surfaces, will shift the compound ring longitudinally to elect engagement of that particular clutch. Ring |39 is a primary control member, as will soon appear.

The shaft 32, like the sleeve l2. is supported in the Walls lli! and of the casing 23. To that end, the wall 8i! is formed with an inwardly extending, annular flange Mil supporting Within it the outer race IM of a roller bearing |42. The inner race |43 of the roller bearing is carried by the sleeve H9 and retained in position by a nut |44 threaded on the end of the sleeve. The wall 85 is provided with an aperture in which is received .the outer race U15 of a roller bearing |46, the inner race lll'! of which is carried by the sleeve 42 and retained by a nut |45 threaded onto the end An annular ring |49 threaded into the end wall S5 aids in retaining the outer race Ulli oi' the bearing in position. Non-rotatably secured to the sleeve 'l2 is a gear |52), and no1?.- rotatably secured to the sleeve |59 is a gear |5| which. form parts of a drive train for the spindle El when the same is to be employed for drilling or some other operation other than thread cutting.

Having described the mechanism for rotating and reciprocating the spindle 2, the control Ineans for the mechanism will now be described. Forming a principal part of this control means is a shifter fork, generally designated |55 (Fig. 7). This shifter fork has a main portion |55 disposed horizontally and transversely of the casing 23 and pivoted at either end on pins |51 projecting inwardly from the side walls |58 of the casing. Extending upwardly from the horizontal portion intermediate the ends thereoit` are fingers |59 in which are trunnioned diametrically projecting pins |55 of an annular collar |5| received in a peripheral groove E62 formed in the ring |39 (see Figs. 1, 2 and 7). At the right end. as viewed in Fig. 7, the shifter fork is formed with an upstanding arm E forming part of a, latching and of a load and fire device. The arm |55 terminates in a bifurcated end |55 engaging a sleeve |51 (see Figs. 3 and 7) forming part of the load and nre device. The sleeve is reciprocable at one end in a bore |63 formed by a tubular extension |69 projecting inwardly from the wall 85 and iS reciprocable at the other end in a bore Hi) formed by a tubular member lll secured to the wall 8|). One end of the sleeve ifs'l is closed by a plug |12 against which bears one end of a compression spring lf3 disposed within the sleeve, the other end cf which bears against a plug VM closing the bore i618 in the tubular extension ltl. On either side of the point of engagement of the arm |65 with the sleeve, the sleeve carries collars that are `adapted to abut the ends of the tubular extension @t9 and tubular member lll, and thus serve as stops limiting the shift of the sleeve |57.

Each collar |15 preferably is faced with a rubber washer il@ serving to eliminate the noise and the shock incident to contact of the collars |15 with the tubular extension or member. It will be noted that the compression spring lf3 acts to shift the sleeve |l to the right, as viewed in Fig. 3, and thus to rock the shifter fork in a clocl wise direction, as viewed in Fig. 3. In Fig. 1, such rocking of the shifter fork is counterclockwise and hence in a direction to effect engagement of the clutch It and thus operation of that drive train, rotating the spindle 2l at a speed higher than the speed of rotation of the lead screw lil.

In order that the arm |65 may form part of a latching device, as above stated, it carries a latch block (Fig. 2) |32 that is formed with a notch or shoulder Iii. Adapted to cooperate with the latch block it!) is a latch, generally designated |32, composed of a rnain part |33 pivoted at one end by a pin lt between ears it of a lug |85 secured to the wall til. An auxiliary part lill is secured for adjustment longitudinally of the main part |33 by means of a screw i353 and a bolt 82) operating in a slot lSil. The auxiliary part |87 has a slight lateral projection itl at its outer end for engaging the shoulder itl of the latch block, while at its inner end it is provided with a block. is?! extending transversely beyond the margins of the latch. This block |92 is, over the length to which it extends beyond the margins of the latch |32, beveled on the face adjacent the lateral projection |95 to form surfaces |93 (see Figs. 2 and "5). latch is constantly urged toward the latch block ll] by a compression spring lill-l bearing at one end in a socket formed in the main part |85 at the other end surrounding and bearing against a plug |95 threaded into the side wall |58 of the casing 23.

The latch device just described serves to hold the shifter fork |55 in the position shown in the drawings against the action of tie compression spring il... The position of the shifter fori; is that in which the clutch control ring it@ causes clutch |23 to be engaged and thus causes rote,- tion of the spindle 2l at a speed lower than the speed of the lead screw lil, with a resultant advance of the spindle as already described. Ff/'ithdrawal of the latch |82 to release the shifter fork to the action of the spring H3 is effected under the control of the spindle 2l. To that end the n is disposed above and parallel with the spin .le 2l' a control rod 269i guided for recirocatory movement at one end in the wall and at the other end in the bracket 26. Adjustahly clamped on the rod 262i) are a first pair of collars 2li! and Slidable on the rod 2M intermediate the collars 2Q! and 292 is parU of a dog movabie longitudinally with the spindle 2'! but permitting rotation of the spindle relative thereto. This dog is disposed on the spindle 21 between collars 2&4 and 205 and normally retained abutting the collar 224 by means of a compression spring 2&6 interposed between the dog and the collar 2F55, Rod 20|) carries a second set of collars 253'! and disposed between these collars is a short, bifurcated arm 208 non-rotatably secured on a rock shaft 23S extending transversely of and journaled in the overarm 25. At its left hand outer end, as viewed in Fig. e, shaft 209 carries non-rotatably thereon a substantially longer depending arm 2|0 terminating in a bifurcated end 2li. This bifurcated end of the arm 2id straddles a rod 2|2 between a pair of collars 2|3 fixed thereon. The rod 212 is supported for axial shifting movement by the wall Si] and the wall of the casing 23. Wall S5 is pr ferably formed with tubular extensions 2M extending in both directions from the wall so as to provide a lengthened bearing surface for the rod 252. Adjustably mounted on the rod 2I2 within the casing 23 is a dog 2 l 9 having a beveled cam surface 225i (see Fig. 3) disposed to engage the cam surface IQB, upon appropriate movement of the rod 2&2, to thereby cam the latch |32 outt wardly away from the latch block lil@ and release the shifter fork to the spring lf3. Such release of the shifter fork occurs when the dog 2% in response to advance movement of the spindle 2l' engages the collar 2&2 and thus shifts the control rod 2d@ to the right, as Viewed in Fig. 3. Such shift of the control rod through the arm 2333, rock shaft 229, and arm 2li) shifts the rod 2|2 and 'thereby causes the dog 259 to engage the block |Q2 and withdraw the latch E62. Such release is, of course, timed to take place when the tool spindle 21 has advanced the desired amount.

In Fig. 3 there is shown a duplicate rod 2|2 carrying a dog 2 IS', the rod and dog being in all respects similar to the rod 2I2 and provided for use should a lower one of the spindles 2l be employed as the control spindle, inasmuch as the block |32 extends below the latch |32 as well as above, it will be apparent that the latch is adapted to be actuated from this lower dog 2 l5' to release the shifter fork without necessity oi any change in construction or even adjustment. This lower rod 2|2, together with the dog 2i9 is shown somewhat enlarged in the enlarged View Fig. 2. A. better conception of the dog and particularly of the cam surface provided may thus be had by reference to this view.

The shifter fork is initially rocked to the poition shown in the drawings, namely. to cause engagement of the clutch |23 and to cock or potentiate the load and fire device under the control of the slide 22. It is restored to neutral position. that is, with both clutches |23 and SM disengaged. under the control cf the spindle 2l. with both the spindle 2l and the slide 22 acting through a common motion translating means, generally designated 225. This device shown primarily in Figs. 4 to 6, 9 and l0. comprises a rod 225 pinned at one end to the end of a clownwardly projecting arm 22'! of the shifter fork. |55, At its other end, this rod is provided on. opposite sides with rack teeth 228 and 229. Pivoted on a vertically disposed pin 23D in recess 23%! in a block 232, secured within the of the machine, is a crank 233 having a short arm 2321 terminating in a segmental pinion meshing with the rack teeth 228. This crank has a longer arm 225 carrying at its Free end a pivoted dog 23B. This dog is by a spring 23'! constantly urged in a clockwise direction, as

viewed in Figs. 9 and 10, to the position shown, and is restrained against further movement in that direction by abutment with a depending lug 238 on the underneath side of the arm 235. The edge of the dog 236 facing toward the pin 236 is beveled to form a cam surface 239. Engageable with this cam surface is a dog 240 carried by the slide 22. This dog is provided with a complementarybeveled cam surface 24| and upon engagement with the dog 236 when the slide is moving forwardly, that is, downwardly, as viewed in Fig. 9, will cam the crank 233 in a clockwise direction thereby shifting the rod 226 in a direction rocking the shifter fork to effect engagement of the clutch |23 and cooking of the load and lire device. During return movement of the slide 22, engagement of the dog 236 by the dog 240 merely pivots the dog 236, permitting the dog 240 to ride by without swinging the crank 233.

Cooperatively engaging the rack teeth 229is a segmental pinion 245 keyedrto the lower end of a vertically disposed shaft 246. The shaft is journaled at its lower end in the block 232 and at its upper end in a bracket 24'l. Near its upper end the shaft 246 has non-rotatably secured thereto a generally triangular plate 248 with the shaft passing through the plate near the apex thereof. Upstanding from the outside base corner of the plate, as viewed in Fig. 4, is a lug 249 disposed in the path of the lower end of an arm 250 fixed on the rock shaft 269. During the retraction of the spindle 21 the dog 203 strikes the collar 26| on the control rod 200, thereby rocking the shaft 206 in a clockwise direction, as viewed in Fig. 3. Consequently in Fig. 5, which is a View opposite to Fig. 3, the arm 250 will be swung in a counterclockwise direction, thereby striking lug 249 and rocking shaft 246 in a counterclockwise direction, as viewed in Figs. 6 and 9. As a result, the rod 226 will again be pulled downwardly, as viewed in Figs. 9 and 10, that is, to the right in Fig. 3, rocking the shifter fork to restore the clutch control ring to neutral position wherein both clutches |23 and |24 are disengaged.

The plate 248 is adapted for employment without change in the cutting of left hand threads.

.To that end, there extends upwardly from the opposite base corner a lug 25| similar to the lug 246, and the rock shaft 209 is provided with a removable spacer sleeve 252 which when removed permits the arm 250 to be shifted inwardly to a position where it will engage the lug 25| and thus rock the shaft 246 opposite to the direction rocked when the arm engages the lug 249.

For a better and more ready understanding of the interrelation of the driving mechanism and the control mechanism just described, the operation of the screw machine for the cutting of right hand threads will be briefly set forth. For that purpose, let it be assumed that the machine and the various parts thereof are in the positions that would be taken just prior to commencement of operation on a new set of work blanks. Under those circumstances, both clutches |23 and |24 would be disengaged, the slide 22 would be in the position shown in Fig. 10, and the plate 248 would still be in the position shown in Fig. 6. Under these conditions, the sleeve 'I2 is driven through the frictional drive means |06 and thus is rotated at the same speed as the lead screw T6. As a consequence, the spindle 2l remains stationary in so far as its axial position is concerned. As the slide 22 moves forwardly to coinvmence a new cycle of operation, the dog 240 strikes the dog 236 and rocks crank 233 in a clockwise direction shifting rod 226 downwardly to the` position shown in Fig. 9, thereby rocking shifter fork |55, to the position shown in the various figures, engaging clutch |23.

In suoli rocking of the shifter fork 55, the latch block itu is carried beyond the end of the latch |82, permitting the same, under the influence of the spring i534, to drop in front of the shouldei` ii on the latch block and thus hold the shifter fork in this position against the tendency of' the load and lire device and oi' any other means to slilit the same to some other position. The sleeve n: is how positively driven through gears iii and li'ii, and this positive drive will, of course, overcome or override the iri'ctional drive means |66. Due to the gear ratio between the gears ii and |15, the spindle l2, though still rotated in a counterclockwise direction, as viewed from the right in Fig. i, is rotated at a slower rate than the lead screw lo. Similarly, the spindle iz is rotated at a slower rate than the work supporting spindle 29, and thus relative to both the lead screw l'u and the work supporting spindle 29 has a clockwise rotation. In consequence, the nut 'u and hence the spindle 21 will be reu forwardly, that is, to the left, as viewed in i'flg. l, to cause engagement of the tool carried by the spindle with the work blank. With such feeding oi the too-l, right hand threads will be formed on the work blank, for, as stated, the tool is rotating clockwise relative to the work blank.

As the spindle 2 advances, it carries with it its dog 2025 which ultimately strikes collar 262 of the control rod mi) and shifts the control rod to the right, as viewed in Fig. 3, to rock the rock shaft 26e and the ariiis, particularly 2i, rigid therewith. Swinging or' trie arm 2li) in turn causes shift of the rod 2 i 2 with resultant engagement of the cam surface 22o of the dog ZIB with the cam surface ist of the block |62 of latch |82. As a result, iatcli '|82 is cammed outwardly releasing the shifter fork to actuation by the load and rire device. As a result, clutch control ring |36 is shifted from the position shown in Fig. 1 directly and without pause through neutral position to a position overlying roller |38 toA effect engagement of the clutch |24. The provision of the frictional drive means for rotating the sleeve 'i2 at an intermediate speed and oi disk clutches for driving the sleeve at the lower or the higher speed makes possible this direct transition from the lower to the higher speed without a pause or `dwell at the intermediate speed and without noise, danger of tooth breakage or other disadvantages inherent in the employment oi' toothed clutches. it is well to remember at this point `that rocking or the shaft zur by engagementof the dog tot with the collar 262 results in a swing- Thus when by the rocking of the shifter fork the plate 248 is rotated in a clockwise direction as viewed uiii Fig. 6 no interference between the arm 250 and the lug 249 occurs.

With the clutch |24 now engaged, the sleeve 'l2 and hence the spindle 2 are rotated at a speed higher than the rotation of the lead screw I6 and of the work supporting spindlel 26. As a consequence, the spindle 2l and its nut 68 have a counterclockwise rotation relative to the lead screw lll and relative to the work blank. The spindle 21, therefore, and the thread cutting tool carried thereby will thus be gradually backed olf and the spindle returned to its innermost or normal or initial position. As the spindle is retracted, dog 203 will engage collar 23| on the control rod 25J@ and thus rock the rock shaft-2% in a counterclockwise direction, as viewed in Fig. 5. The arm 258 then will engage lug 249 and will rotate shaft 246 in a counterclockwse direction, as viewed in Fig. 6, and will thus, through the rack and pinion connection, draw the rod 225 downwardly to the position shown in Fig. 10. The shifter fork will thus be rocked in a direction to disengage the clutch |24. When the clutch contro-l ring its reaches its neutral position drive of the sleeve 'l2 will have been restored to the frictional driving means |85, with the result that further movement of the spindle will be arrested as well as further rocking of the shifter fork. The parts will thus remain in this neutral position.

It is believed apparent from the foregoing that there has been provided vastly improved actuating mechanism for the spindle and vastly improved control means for the actuating means. The construction of the actuating mechanism is extremely simple with little that can get out of running order. The employment of the frictional drive means |66 and of the frictional disk clutches |23 and |24 makes possible quick and rapid shifting without noise or shock to the mechanism, and makes possible a shift directly from one speed through the intermediate speed to the other speed without necessity of a pause at the intermediate speed or neutral position of the clutch control ring. This mechanism further eliminates the necessity of hair line adjustments to assure that the teeth of the clutches will mesh at the proper time and without injury.

I claim as my invention:

l. In a screw machine, a lead screw, means continuously rotating the lead screw, a spindle rotatably and reciprocably mounted and having a nut threadedly engaging said lead screw, and means adjustable for rotating said spindle at different rates to hold the same axially stationary or shift the same longitudinally relative to said -lead screw including a constantly engaged frictio-nal drive means which, when operating alone, rotates said spindle at the same speed and in the same direction as said lead screw and thus holds the spindle axially stationary.

2. In a screw machine, a rotatably mounted lead screw, means continuously rotating said lead screw, a spindle rotatably and reciprocably mounted and having a nut threadedly engaging said lead screw, means including a constantly engaged irictional drive means which, when operating alone, rotates said spindle at the same speed and in the same direction as the lead screw to hold the spindle against axial movement, and means selectively engageable with the spindle and rotating said spindle at a speed below that of Said lead screw, to produce axial movement of the spindle in one direction, or at a speed above that of said lead screw, to produce axial movement of the Spindle in the opposite direction.

3. In a screw machine, a rotatably mounted lead screw, means continuously rotating said lead screw, a spindle rotatably and reciprocably mounted and having a nut threadedly engaging said lead screw, means including a constantly engaged frictional drive means which, operating alone, rotates said spindle at the same speed and in the same direction as said lead screw, a rst drive train including a rictional clutch capable of overcoming said frictional drive and rotating said spindle slower than said lead screw and a second drive vtrain including a irictional clutch capable of overcoming said frictional drive and rotating said spindle faster than said lead screw.

4. In a screw machine, a rotatably mounted lead screw, means continuously rotating said lead screw, a spindle rotatably and reciprocably mounted and having a nut threadedly engaging said lead screw, means including a constantly engaged frictional drive means which, operating alone, rotates said spindle at the same speed and in the same direction as said lead screw, a first drive train including a normally disengaged frictional clutch operable upon engagement to overcome said frictonal drive and rotate said spindle slower than said lead screw, a second drive tra-in including a normally disengaged irictional clutch operable upon engagement to overcome said frictional drive and rotate said spindle faster than said lead screw, and means for selectively causing engagement of one or the other ci' said clutches.

5. In a screw machine, a rotatably mounted lead screw, means rotating said lead screw at a constant speed, a spindle having a nut threadedly engaging said lead screw, a sleeve rotatably mounted and having a splined connection with said spindle to impart rotation thereto while permitting movement of the spindle longitudinally thereof, means including aconstantly engaged frictional drive means which, when operating alone, rotates said sleeve at` the same rate and in the same direction as the lead screw to hold the spindle against axialv shift, and normally disengaged means operable upon engagement to override said frictional drive means and rotate said sleeve al; a speed higher or lower than the speed of the lead screw to advance or retract the spindle, said last mentioned means including a pair of selectively engageable friction clutches.

6. In a screw machine, a drive shaft, a rotatably mounted sleeve, a spindle received partially within the sleeve and supported thereby, a connection between said sleeve and spindle causing said spindle to rotate with the sleeve while permitting movement 0f the spindle longitudinally thereof, a rotatably mounted lead screw, a nut carried by said spindle threadedly engaging said -lead screw, and means for rotating and reciprocatingsaid spindlecomprisng a geared connection between said shaft and said lead screw to rotate the latter at a constant speed, a constantly engaged frictional drive means between said geared connection and said sleeve to drive the latter at the same speed and in the `same direction as said lead screw, a drive train between said shaft and said sleeve including a normally disengaged clutch and operable when the clutch is engaged to rotate said sleeve slower than said lead screw, a second drive train between said shaft and said sleeve including a normally disengaged clutch and `operable when the clutch is engaged to rotate said sleeve faster than said lead screw, and means for selectively causing engagement of one or the other clutch.

7. In a screw machine, a drive shaft, a rotatably mounted sleeve, a spindle received partially within the sleeve and supported thereby, a ccnnection between said sleeve and spindle causing said spindle to rotate with the sleeve while permitting movement of the spindle longitudinally thereof, a rotatably mounted lead screw, a nut carried by said spindle threadedly engaging said lead screw, and means for rotating and reciprocating said spindle comprising a geared connectionv between said shaft and said lead screw which rotates the latter at a constant speed, a constantly engaged frictional drive means between Asaid geared connection and said sleeve which drives the latter at the same speed and in the same direction as said lead screw, a pair of drive trains between said shaft and said sleeve, each including a gear fast on said sleeve, a gear rotatable on said shaft and a frictional clutch ior locking the last mentioned gear for rotation with said shaft, one of said drive trains being operable to rotate said sleeve slower than said lead screw, and the other being operable to rotate said sleeve faster than said lead screw, and means govern- -ing engagement of said clutches.

3. In a screw machine, a rotatably mounted lead screw, a spindle having a nut threadedly engaging said lead screw, a rotatably mounted sleeve surrounding a portion of said spindle supporting the saine for rotation with the sleeve and for longitudinal movement relative to the sleeve, means for rotating the lead screw including a gear non-'rotatably secured on the lead screw, means for rotating said sleeve at the Same rate as said lead screw to hold the spindle against longitudinal movement `relative to said lead screw including a frictional drive means non-rotatably secured to said sleeve and yieldably engaging said gear, and means for overcoming said frictional drive means to rotate said sleeve slower or faster than said lead screw to eiect axial shift or said spindle in opposite directions.

9. In a screw machine, a rotatably mounted lead screw, means for rotating the lead screw including a gear non-rotatably secured on the lead screw and having an axially projecting annular flange, a spindle having a nut threadedly engaging said lead screw, a rotatably mounted sleeve surrounding a portion of said spindle supporting the same for rotation with the Sleeve'and for longitudinal movement relative to the sleeve and 'projecting at one end within the annular flange on said gear in radial spaced relation thereto, and frictional drive means for `rotating said sleeve at the same rate as said lead screw interposed between sai-d sleeve and said annular flange cornprising a rst part non-rotatably held relative to said sleeve, and a second part yieldably urged into constant engagement with said annular flange, and means for overcoming said rictional drive means to rotate said sleeve slower or faster than said lead screw to eiect axial shift of said spindle in opposite directions.

1G. In `a screw machine, a spindle rotatably and reciprocably mounted, and means for rotating and reciprocating said spindle including a constantly engaged frictional drive means which, when operating alone, rotates said spindle at 'an intermediate speed, a rst drive means capable of overcoming said frictional drive and rotating said spindle at a lower speed including a frictional clutch, and a second drive means capable of overcoming said irictional drive and rotating said spindle at a higher speed including a frictional clutch. i

ll, In a screw machine, a spindle rotatably and reciprocably mounted, and means for rotating and reciprocating said spindle including a constantly engaged frictional drive means which, when operating alone, rotates said spindle at a particular speed, and additionally engageable means overriding said frictional drive and rotating said spindle at a different speed.

l2. In a screw machine, a spindle rotatably mounted, means including a constantly engaged yfrictional driving connection which, when opervating alone, rotates said spindle at an intermediate speed, and additional driving means overriding said frictional driving connection and selectively rotating said spindle at a speed higher or a speed lower than the intermediate speed, said last mentioned means including a pair of valternately engageable disk clutches.

13. In a screw machine, a reciprocably mounted slide, means for reciprocating said slide, a rotatable spindle mounted for axial sliding movement, driving means for advancing or retracting said spindle, and means i'or governing said spindle driving means comprising means actuated by said slide during the approach movement thereof to initiate advance of said spindle, and means controlled by said spindle operable after a predetermined advance oi said spindle to cause said driving means to retract said spindle and operable upon return of said spindle to arrest operation oi said driving means.

le. In a screw machine, a reciprocably mounted slide, means for reciprocating said slide, a rotatable spindle mounted for axial sliding movement, driving means for advancing or retracting said spindle, and means for governing said driving means comprising a control member having a neutral position wherein the driving means is ineiiective to advance or retract said spindle, a position to one side of neutral wherein the driving means is operative to advance the spindle, and a position to the other side of neutral wherein the spindle driving means is operative to retract the spindle, a load and iire device operable to shift said control member from its spindle advancing position through neutral to its spindle retracting position in a single uninterrupted movement, means actuated by said slide to position said control member in its spindle advancing position and to cock said load and lire device, a latch for holding said member in its spindle advancing position, means governed by said spindle for releasing said latch and placing said control member under the control of said load and fire device after a predetermined advance of said spindle, and means actuated by said spindle upon return thereof to starting position to return said control member to neutral `position.

15. In a screw machine, a reciprocably mounted slide, means for reciprocating said slide, a rotatable spindle mounted for axial sliding movement, means for advancing said spindle, means for retracting said spindle, and means for governing said spindle advancing and retracting means comprising a control member having a neutral position wherein both spindle shifting means are inoperative, a position to one side of neutral wherein the Spindle advancing means is operative, and a position to the other side of neutral wherein the spindle retracting means is operative, a load and fire device operable to shift said control member from its spindle advancing position through neutral to its spindle retracting position, means actuated by said slide to position said control member in its spindle advancing position and to cock said load and dre device, a latch for holding said member in its spindle advancing position, means governed by said spindle for releasing said latch, and means governed by said spindle for returning said control member to neutral position.

16. In a screw machine, a reciprocably mounted slide, means for reciprocating said slide, a rotatable spindle mounted for axial sliding movement, means for advancing said spindle inelud- .means including a control n ing a clutch, means for retracting said spindle including a clutch, and means for governing said clutches comprising a control member having a neutral position wherein both clutches are vdisengaged, a position to one side ci neutral wherein a clutch is engaged causing advance of the spindle, and a position to the other side of neutral wherein a clutch is engaged causing a retraction of the spindle, a load and fire device operable to shift said control member from its spindle advancing position through neutral to its spindle retracting position, means actuated by said slide to position said control member in its spindle advance position and to cock said load and iire device, a latch for holding said member in its spindle advance position, means governed by said spindle for releasing said latch, and means governed by said spindle for returning said control member to neutral position.

17. In a screw machine, a reciprocably mounted slide, means for reciprocating said slide, a rotatable spindle mounted for axial sliding movement, means for advancing said spindle including a first normally disengaged clutch, means for retracting said spindle including a second normally disengaged clutch, and mea-ns for governing said clutches comprising an annular ycontrol ring having a neutral position wherein both clutches are disengaged, a position to one side of neutral wherein the first clutch is engaged, and a position to the other side of neutral wherein the second clutch is engaged, a shifter fork engaging said annular contro-l ring to determine the position thereof, a load and lire device biased constantly to urge engagement of said kfirst clutch, means actuated by said slide and acting through said shifter fori: to effect engagement of said second clutch and to cocl; said load and nre device, a latch cooperable with said shifter fork for holding the same in cool-:ed position, means governed by said spindle for releasing said latch after a predetermined advance of said spindle, and means governed by said spindle upon retraction thereof for returning said control member to neutral position.

18. In a screw machine, a reciprocably mounted slide, means for reciprocating said slide, a rotatable spindle mounted for axial sliding movement, means for advancing said spindle, means for retract-ine said spindle, and means for governing said spindle advancing and retractng aber having a neutral position wherein both s indie shifting means are inoperative, a position to one side of neutral wherein the spindle advancing means is operative, and a po ion to the lother side of neutral wherein the spindle retractng means is operative, and means actuated by said slide to position said control member in its spindle advance position including a rod having rack teeth formed therein and connected to said control member, crank having a iirst arm terminating in teeth meshing ith said rack and a second arm, a dog near the end of said second arm pivotally mounted to permit pivoting in one direction but restrained against pivoting in the opposite direction, and a dog by slide and positioned to engage said pivoted dog during the af- Vance of said slide in a manner to sv g said crank and shift said control member I om its neutral to its spindle advance position. Y

19. In a screw machine, a reciprocably mounted slide, means for reciprocating said slide, a rotatable spindle mounted for axial sliding movement, means for advancing said spindle, means for retractng said spindle, and means for governing said spindle advancing and retracting means including a control member having a. neutral position wherein both spindle shifting means are inoperative, a position to one side of neutral wherein the spindle advancing means is operative, and a position to the other side of neutral wherein the .spindle retracting means is operative, a bar operatively connected with said control member and having racks formed on opposite sides thereof, a iirst pinion providing means meshing with one of the racks on said bar, a second pinion providing means meshing with the other rack on said bar, a dog on said slide cooperable with said first pinion means during ad- Vance of said slide to shift said control member from its neutral to its spindle advancing position, and means actuated by said spindle upon return thereof to s'tartinv position to actuate said second pinion providing means to return said control mernber from its spindle retracting position to neutral.

20. In a screw machine, a reciprocably mounted slide, means for reciprocating said slide, a rotatable spindle mounted for axial sliding movement, means for advancing said spindle, means for retracting said spindle, and means for governing said spindle advancing and retracting means including a control member having a neutral position wherein both spindle shifting means are inoperative, a position to one side of neutral wherein the spindle advancing means is operative, and a position to the other side of neutral wherein the spindle retracting means is operative, a shifter fori; having a yoke engaging said control member to shift the same to its various positions, an arm, a load and re device engaged by said arm at its upper end and a latch block, means actuated by said slide to rock said shifter i'ork to the spindle advancing position of said control member and for cooking said load and nre device, a latch constantly urged toward engagement with said latch block and operable to hold said shifter fork with said control member in spindle advancing position, and means actuated by said spindle aiter a predetermined advance thereof to withdraw said latch and release said `shifter iork to the action of said load and dre device for sluiting said control member uninterruptedly from its spindle advancing position through neutral to its spindle retracting position.

2l. In a screw machine, a reciprocably mounted slide, means for reciprocating said slide, arotatable spindle mounted for axial sliding movement, means for advancing said spindle, means for retracting said spindle, and means for governing said spindle advancing and retracting means including a control member having a neutral position wherein both spindle shifting means are inoperative, a position to one side of neutral wherein the spindle advancing means is operative, and a position to the other side of neutral wherein the spindle retracting means is operative, a shifter fork having a yoke engaging said control member to shift the same to its various positions, an arm, a load and re device engaged by said arm at its upper end and a latch block, means actuated by said slide to rock said Ashifter fork to the spindle advancing position of said control member and for cooking said load and lire device, a latch constantly urged toward engagement with said latch block and operable to hold said shifter fork with said control member in spindle advancing position, a dog operable to engage said latch and disengage the same from said latch block, and means for actuating said dog including a control rod extending parallel with said spindle and shiftable longitudinally, means carried by said spindle operable upon a predetermined advance of said spindle to shift said control rod, and a rock shaft having a pair of arms rigid therewith, one engaging said control shaft and the other connected to actuate said dog and proportioned to magnify the movement of said control rod.

22. In a screw machine, a reciprocably mounted slide, means for reciprocating said slide, a rotatable spindle mounted for axial sliding movement, means for advancing said spindle, means for retracting said spindle, and means for governing said spindle advancing and retracting means including a control member having a neutral position wherein both spindle shifting means are inoperative, a position t0 one side of neutral wherein the spindle advancing means is operative, and a position to the other side of neutral wherein the spindle retracting means is operative, a load and fire device operable to shift said control member irom its spindle advancing position through neutral to its spindle retracting position, means actuated by said slide to position said control member in its spindle advancing position and to cock said load and nre device, latch means for holding said control member in its spindle advancing position and said load and nre device in cocked position, a control rod axially shiftable mounted parallel with said spindle, a pair of axially spaced collars on said control rod, a dog carried by said spindle disposed between said collars and positioned to engage one collar and shift said control rod in one direction as the spindle approaches the end of its advancing movement and to engage the other collar and shift said control rod in the opposite direction as the spindle approaches the end of its retracting movement,

lil

a rock shaft having a first arm rigid therewith and operatively associated with said control rod to be swung by movement of the rod, means for releasing said latch means including a second arm Xed on said rock shaft, and means for returning said control member from its spindle retracting to its neutral position including a third arm rigid with said rock shaft.

23. In a screw machine, a rotatably mounted lead screw, a spindle rotatably and reciprocably mounted and having threaded engagement with said lead screw, means constantly rotating one of said parts, means including a constantly engaged frictional drive connection which, when operating alone, rotates the other part at the same speed and in the same direction as said one part to prevent relative axial movement of said parts, and means engageable with said frictionally driven other part overriding its frictional drive and rotating said part at a different speed, thereby causing axial movement of the spindle.

24. In a screw machine, a rotatably mounted lead screw, a spindle rotatably and reciprocably mounted and having threaded engagement with said lead screw, means constantly rotating one of said parts, means including a constantly engaged frictional drive connection which, when operating alone, rotates the other part at the same speed and in the same direction as said one part to prevent relative aXial movement of said parts, and means selectively engageable with the said frictionally driven other part overriding its frictional drive and rotating said part at a speed below that of the said one part, to produce axial movement of the spindle in one direction, or at a speed above that of said one part, to produce axial movement of the spindle in the opposite direction.

J UDSON H. MANSFIELD- 

